1. Technical Field
The present invention relates to a resonator element, a resonator, an oscillator, an electronic apparatus and a moving object.
2. Related Art
An AT-cut quartz crystal resonator element exhibits a thickness shear vibration in a vibration mode of main vibration for excitation. Since the AT-cut quartz crystal resonator element is suitable for miniaturization and increase in frequency and provides a cubic curve having an excellent frequency-temperature characteristic, the AT-cut quartz crystal resonator element is used in various apparatuses such as a piezoelectric oscillator and an electronic apparatus.
JP-A-2002-198772 discloses an AT-cut quartz crystal resonator element having an inverted mesa structure that includes a thin vibrating section and a thick section provided around the entire periphery of the vibrating section. The AT-cut quartz crystal resonator element is fixed to a package through an adhesive agent in one end portion of the thick section. In a state where the AT-cut quartz crystal resonator element is cantilevered, if an acceleration in a thickness direction is applied to the AT-cut quartz crystal resonator element, a tip section (the vibrating section) is deformed, which causes a problem in that a vibration characteristic (frequency characteristic) is not stable. In particular, in the AT-cut quartz crystal resonator element disclosed in JP-A-2002-198772, since the thick section is formed over the entire periphery of the vibrating section and the weight of the tip section is heavy, the influence on the acceleration is large, and accordingly, the amount of frequency deviation is also increased. Here, in order to reduce the deformation of the tip section (vibrating section), a method of increasing the thickness of the thick section to enhance the rigidity may be considered. However, if the thickness of the thick section increases, the accuracy of formation of the vibrating section in wet etching is decreased, which causes a problem in that a vibration characteristic of an obtained resonator element does not reach a predetermined characteristic.